Telecommunications technologies provide users with great tools and communication capabilities. Especially when implemented on mobile devices, telecommunications has allowed users to enjoy great connectivity whether it be by phone, internet, text messaging, emails and more. One aspect of telecommunications is geo-location. Mobile devices can locate themselves using various technologies. Wireless networks (such as Wi-Fi®) often have a geographical location coded into its router. Cellular services also provide geo-location capabilities. One of the most common geo-location technologies is the Global Positioning System (GPS). Different telecommunications and geo-location technologies use a variety of electromagnetic, radio, acoustic, and other communications platforms. Other areas of the world may use different technologies such as the Galileo positioning system in Europe, the Indian Regional Navigation Satellite System in India, and the Beidou Navigation Satellite System in China, among others.
GPS relies on satellites positioned high above the Earth. These satellites constantly transmit messages. The messages include 1) when the message was sent, and 2) the satellite position when the message was sent. GPS receivers on the ground receive this data and can calculate their distance to a satellite using the speed of light. When a GPS receiver knows its distance from multiple satellites it can determine an intersection point, i.e. its location. In practice GPS receivers usually need measurements from four or more GPS satellites to provide an accurate location. Typically, a GPS receiver on the ground has access to eight or nine GPS satellites at any given time.
Wireless (such as Wi-Fi®) and cellular networks have geo-location capabilities that function differently than GPS. A wireless (such as Wi-Fi®) or cellular device may have a MAC (media access control) address, a unique identifier, that can be used for location purposes. Cellular devices can connect to cellular base stations. The network operator, or other entity, may then be able to locate a cellular device by knowing what base station the cellular device is within the range of. A device may also have a unique IP address and this can be used to find the device's location.
Telecommunications and geo-location services can see their usefulness decline when there is interference. Some technologies or radio waves depend on line-of-sight, meaning that a transmitter and receiver must be in line-of-sight to each other because the communication waves used will generally not travel around obstacles. Obstacles can include buildings, cars, hills, mountains, the curvature of the earth and other objects. Some telecommunications systems are not limited to line-of-sight, but buildings, hills and the like can still cause interference due to electromagnetic waves bouncing off the objects and going in various directions. A particular difficulty can arise when user with a mobile device is inside of a building. Cellular, GPS and other networks can have a hard time communicating due to the interference caused by the walls and floors of the building. The amount of interference can depend on the construction materials in the building, distance from a transmitter, and other factors.
GPS systems are prone to interference problems when a user is inside a building. When a satellite device is blocked from access to the sky (e.g. inside a warehouse, plane, factory) it cannot report its location and often it cannot receive the GPS signal. The satellite unit tries to get GPS data and send satellite or radio messages, needlessly draining it's battery for messages that never will be received. For a one-way satellite device, it doesn't know that its messages are not being received or that it's in a location where it cannot receive GPS or send messages.
Some mobile devices try to overcome interference problems by implementing multiple geo-locations services. If a user is inside a building and can't access GPS, then the geo-location services of cellular networks will be used. If cellular is unavailable then Wi-Fi geo-location may be available, etc. Various of these technologies have different margins of error. For instance a user may want to solely use the accuracy of the GPS system, even when located inside a building. Businesses may use geo-location to monitor employees or vehicles and may wish to rely on GPS instead of cellular geo-location. Therefore a system is needed that can help extend the reach of GPS or other geo-location systems to the inside of buildings or other locations.
A system is also need with multiple geo-location functionalities, such that if one system is down or a device is out of coverage then back-up systems can take over and provide location to a user trying to track inventory or devices of some kind.